They are herbaceous plants or small shrubs growing to 1–4 m tall. The leaves are opposite, simple ovate to lanceolate, with an entire or crenate margin; they are often aromatic. The blue or white flowers are pollinated by butterflies and bumblebees. The fruit is a four-valved capsule containing four seeds.[3][4][5]

Though several Caryopteris species are grown in botanical gardens, as ornamental plants the species have largely been superseded in gardens by the hybridCaryopteris × clandonensis (C. incana × C. mongholica). The accidental cross that produced it occurred in the garden of Arthur Simmonds at Clandon, near Guildford, Surrey.[6] In 1930, wishing to propagate C. mongholica, he gathered seeds from a plant that was growing near C. mastacanthus. When the seedlings eventually flowered in their second year, hybrids appeared. The final selection, however, was made of a self-sown volunteer that appeared under C. mastacanthus, and eventually smothered it. It began winning Royal Horticultural Society medals in 1933.[7][8] This small, deciduous, aromatic shrub has grey-green leaves and produces masses of blue flowers in late summer.[9] There are several cultivars with flowers in shades of blue or white, including 'Blue Mist', 'Heavenly Blue', 'Longwood Blue', 'Dark Knight', 'Summer Sorbet' and 'Pershore'.

Caryopteris × clandonensis, an unusual plant in American gardens in the 1960s,[13] has become more familiar there, especially in xeriscaping.

Like Buddleja, the woody stems can die back in the winter, particularly in colder climates and on heavy soils. They prefer well-drained, sandy soil in full sun, but does not need especially rich soil or constant moisture.

Leaves and herbaceous stems have a terpene aroma like eucalyptus, especially when lightly bruised.